216 REPORT OF THE COMMISSIONER OF FISHERIES. 
appeared. £2. coli is found only occasionally, and then on the ebb 
tide. Another zone of pollution spreads out from Warren River, 
however, and at station 1, buoy No. 1, 3 miles below the town of 
Warren, evidences of it can be discovered; but at station 6, 4 miles 
below this town, examination fails to reveal the presence of sewage 
bacteria. Samples from the Prudence Island and Wickford oyster 
beds contained no colon bacilli; neither did the samples collected over 
the southern parts of the Rocky Point oyster ground, so that the 
Providence River, 8 miles below the chief sources of contamination, 
ceases to be a polluted stream. If sewage is present in the water below 
this point, it is in too great dilutions to be recognized in the 1 e¢. ¢, 
samples that were used in this work. The waters of Narragansett 
Bay are also free from sewage pollution. 
The next series of samples was collected in or near the Kickemuit 
River. Three stations were located in this part of the bay: Station 1, 
over the oyster layings south of Warren Neck; station 2, just inside 
the mouth of the Kickemuit River; and station 3, about three-quarters 
of a mile farther up the river. £2. cold was found in but one sample 
from the oyster beds south of Warren Neck, which are 4 miles from 
the Fall River sewer. Finally, three stations near the entrance to 
Mount Hope Bay were visited—stations 1 and 2, over the oyster bed 
north of Common Fence Point, 6 and 6% miles, respectively, from Fall 
River; and station 3, over the Bristol Ferry bed, 74 miles below the 
city. But a single sample contained the colon bacillus. This was 
collected at station 3, off Bristol Ferry, and the presence of the organ- 
ism was probably due to some local contamination rather than to the 
sewage from Fall River, since samples from stations 1 and 2, consider- 
ably nearer the chief source of pollution, did not contain this bacillus. 
As a final test of the distribution of sewage bacteria in the river, an 
attempt was made to estimate the number of colon bacilli per cubic 
centimeter in this water. For this test lactose agar plates containing 1 
per cent neutral red were inoculated directly with the water to be 
tested, and incubated forty-eight hours at 42° C. After this period, 
the colonies developing were examined, and those exhibiting the char- 
acteristic appearance of /. colé on this medium were counted. It was 
impossible to study each separate colony in pure culture, therefore 
these figures have but an approximate value. Four plates were made 
from each sample; and the figures given in Table VII represent the 
average number of characteristic colonies developing within the given 
time. The samples used in this test were collected (October 21, 1901, 
tide rising) at the stations indicated on the map on page 203. The 
first sample was taken near the sewer outfall at Fields Point; the 
others at places farther down the river. 
